Akonadi

The data storage access mechanism for all PIM (Personal Information Manager) data in KDE. This allows various applications to access the required information in one place. Note that use of Akonadi does not change data storage formats (vcard, iCalendar, mbox, maildir etc.) - it just provides a new way of accessing and updating the data.

Baloo

Baloo is a file indexing and search service that Dolphin and Elisa use to get metadata for files and to allow global searches. In a terminal type, balooctl check to find out whether an index was created already. balooctl disable and balooctl status are helpful instructions as well.

Dolphin

The default file manager in KDE Plasma. It has a side panel (Places), but navigation is mainly by the breadcrumb trail above the main window. It has various advanced features such as split windows and individual views in different windows. Mounting and umounting USB devices can be done in the side-panel. Other directories can be added to the Places panel. A Tree view is also possible.

KHTML

KHTML is a HTML rendering engine that was the base of WebKit, the engine that powers many browsers still in use today (e.g. Safari).

Kickoff

Kickoff is a launch menu in KDE Plasma in which apps are sorted by functional groups. Right-click also offers the possibility of adding applications to the desktop or panel. Rapid access to a less-used application is made possible with the search box. There are also alternatives, such as the fullscreen app dashboard.

Phonon

Plasma

Plasma is the desktop environment from KDE. It is the part of the desktop that you can see. Plasma also acts as a glue between panels, plasmoids and Kickoff. Plasma Mobile allows Plasma to run on smartphones and uses the same underlying code base.

Qt

(Pronounced "cute") A framework/toolkit for writing cross-platform applications. It is used by many cross-platform applications such as Krita, GoogleEarth and many others. Qt forms the underlying library KDE software is built on.

X Server

The X Server represents a basic layer upon which the various GUIs like the KDE Plasma desktop are built. It manages the basic mouse and keyboard input (from the local host as well as from remote hosts) and provides elementary graphic routines to draw rectangles and other primitives.